1. Field of the Invention
This invention relates to a system for optically detecting flaws in bottles, cups, bowls, cans, and various other containers or like articles. A more specific aspect of the invention concerns such a system for automatically detecting flaws in used and cleaned bottles for beverages or liquors, prior to the refilling of such bottles. By the term "flaws" are meant cracks, breaches, fissures, scratches, adhering foreign matter, and any other imperfections detectable by the system of this invention.
2. Description of the Prior Art
Bottles for some beverages or liquors are recycled; that is, they are recovered from the consumers, cleaned, and put to reuse. Bottle cleaning machines in current use are such, however, that they may not necessarily make the bottles free of all foreign matter firmly sticking thereto. Further, some bottles may have cracks and similar defects formed therein. All such faulty bottles must be discriminated from flawless ones before they are refilled, and should not be reused from the standpoint of hygiene or of the forestallment of actual or potential danger.
According to a typical conventional apparatus for the detection of bottle flaws, a light source underlying a bottle to be tested irradiates the complete surface of its bottom. Disposed at the mouth of the bottle, a photodetector senses the presence of a flaw, if any, in the bottle from the intensity of the incident light that has passed through its bottom.
An objection to this prior art apparatus is its comparatively poor ability of detecting localized flaws and those lying adjacent to the bottom perimeter or on the side wall of the bottle. This drawback arises principally from the application of light only to the bottom of the bottle and from the insufficient intensity of the light. Additionally, since the light falls on the bottle at one time, the photodetector is required to sense its possible flaw from a small change in the incident radiation.
Another objection to the prior art apparatus is its inability, or at least very poor ability, to detect such transparent foreign matter as cellophane adhering to a bottle. This is an inevitable result of its operating principle of sensing flaws in a bottle from the intensity of the light that has penetrated its bottom.